Conventional IR image-based tracking systems, for example those used in missile-based tracking systems for guiding missiles, typically use only one kind of tracking mechanism, such as a correlation-based tracker, to recognize a target's IR signature within an IR image. A target's IR signature can vary, for example, depending on the time of day, the character of objects and terrain near the target, atmospheric conditions, aspect and depression angles, and a distance of the target from the IR image capture mechanism that provides IR image frames to the tracking system. The IR target signature can vary depending on a distance from the target because the size of the target within an IR image frame and therefore the number of pixels in the IR image frame on the target will vary depending on the distance. When environmental conditions or other situations sufficiently alter a target's IR signature, the tracking mechanism can cease to recognize the target in a realtime IR image frame provided to the tracking mechanism, thereby “losing” the target. When a tracking mechanism loses a target in a number of consecutive image frames the tracking mechanism may lose the track of the target.
For example, when a target such as a battle tank moves behind another object so that an outline of the tank is partially hidden behind the object, the remaining outline in the IR image provided to the correlation-based tracker may not provide enough clues for the correlation-based tracker to identify or see the tank in the image. If the correlation tracker does not identify the tank in a number of consecutive image frames, the correlation-based tracker can lose its track of the tank. When the tracker loses its track of the tank, a device being guided by the correlation-based tracker can be guided towards an object which is not the tank, i.e., not the intended target.
Different kinds of tracking mechanisms have different strengths and weaknesses. For example, feature-based trackers are often better than correlation-based trackers at identifying a target whose outline is partially hidden or missing, but are also slower. This can be problematic, for example, in situations where a target rapidly changes position relative to a missile guided by the tracking system.
Accordingly, a need exists for a tracking system that is robust, accurate and effective across a variety of different situations and environmental conditions.